Would suggest you get a copy of his birth cert to establish his mothers maiden name (unless you already know it)
You would then have to use the births index to establish the names of any other children. From the September quarter of 1911 the birth index shows the mothers maiden name alongside the entry.
The FULL BMD index is now available to search free of charge at
www.ancestry.co.uk. You will find it described as England & Wales, BMD Index (Beta)
